From 6bdfd49b2066c4ee9e8e55ded25c129f3d845f7f Mon Sep 17 00:00:00 2001
From: guipublic <47281315+guipublic@users.noreply.github.com>
Date: Fri, 13 Oct 2023 15:14:07 +0200
Subject: [PATCH] fix: do not perform dead instruction elimination on mod,div
 unless rhs is constant (#3141)

---
 .../noirc_evaluator/src/ssa/ir/instruction.rs     | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/compiler/noirc_evaluator/src/ssa/ir/instruction.rs b/compiler/noirc_evaluator/src/ssa/ir/instruction.rs
index f748aa040a1..badc1e82d50 100644
--- a/compiler/noirc_evaluator/src/ssa/ir/instruction.rs
+++ b/compiler/noirc_evaluator/src/ssa/ir/instruction.rs
@@ -239,10 +239,19 @@ impl Instruction {
 
     pub(crate) fn has_side_effects(&self, dfg: &DataFlowGraph) -> bool {
         use Instruction::*;
-
         match self {
-            Binary(_)
-            | Cast(_, _)
+            Binary(binary) => {
+                if matches!(binary.operator, BinaryOp::Div | BinaryOp::Mod) {
+                    if let Some(rhs) = dfg.get_numeric_constant(binary.rhs) {
+                        rhs == FieldElement::zero()
+                    } else {
+                        true
+                    }
+                } else {
+                    false
+                }
+            }
+            Cast(_, _)
             | Not(_)
             | Truncate { .. }
             | Allocate